Method of making evaporators



June 5, 1945. B. c. JOHNSON 7,

METHOD OF MAKING EVAPORATORS Filed Dec. 12, 1940 3 Sheets-Sheet l June 5, 1945.

B. c. JOHNSON METHOD OF MAKING EVAPORATORS 3 Sheets-Sheet 2 ,Filed Dec. 12, 1940 7 271/227 0r 7 fiannara C. Johnson June5, 1945. B. c. JOHNSON METHOD OF MAKING '.EVAPORATORS 3 Sheets-Sheet 3 Filed Dec. 12, 1940 2271/52? DI" Ear/ 4rd C. Johnson Patented June 5, 1945 UNITED STATES PATENT oiFFicE r 2,377,557 METHODDF MAKme'fEvAnoRa'rons Bernard C. Johnson, Libertyville', 111.; assignor to Houdaille-Hershey Corporation; :Detroit; Mich, a corporation of Michigan .Application December 12, 1940; Serial 'No 369,722

1 Claim. (o wee-157 .3)

@This invention'relates to methods for forming rounded edges on metal articles to eliminate sharpaangles "in order that coating material :will imitlormly cover the articles.

Specifically this invention relates to, thepresszingrof'l the-"a edgesrzandzaperture mouths v of cisheet 'metal evaporatortunits 'to-eliminate all sharp: corlnersttherefrom inorderathat the evaporator unit scan be'iiuniformlyw coated with protective i films such aslzinc.

awhile fthed invention will be hereinafter specificallyudescribed in connection withzsheet-metal evaporator "units, it tShO'Llld be understood that therprinciples of the invention 1 are applicabl to :metal articlesin general.

Metal articles havingsharp edges cannot "be ruxfiformly coated since-the coating "film will be "quite "thin'at'these 'edges and, in numerous instancesfithe sharpedgeswill project through the film. ifn'the manuf actureof sheet metal evapo-:-..

rator unitS" from inexpensivemetals such as mild 'steeL it isnecessary to thoroughly protect all ex- *terior surfaces of the unit with aproteeting film.

fsuch she'et metal evaporator units are usually M k galvanized ortinned, and itis very difficult to 1 :cdverthe 'sharp1edges;.of the unit with sucha protective metal film inasmuch as thefilm will tdrawthin oft-break entirely at'lthe edgesofthe :arti'cles.

The;present'inventionnow overcomes the here- ,tofore' encountered difiiculty by dressing allisharp edges and corners of a sheetmetalevaporator Ju'riitto, provide rounded contours thereon which ;.are readily covered with protective film.f.The "dressing operations can he performed by working .501 pressing the, peripheral edges and annula aperture mouths. of the sheet metal unit. For

exampleathegsheetimetal can beipassed between grooved rollers which will round off the peripheral nedgesptithe unit. l-eAnynaperturesm in the unit can 1 the-i die-rpressed to round-off the sharp aperture tm-ouths. lfilhese dressing operations. ar preferab, ly eflected priormto thelloending of .the unit z-intoqrits final shape and while the. same. is still .in h

we flat condition. l L r r La-Iti-is -them an. object. of this invention to. pre- .parei-thesedgeslof metali-articles for. coating by "dressing tthese edges to s form a round {contour rthereon. A 3 h Anotherobject.ofitheinvention is to worlgthe rmetat edges of sheet metal articlesinto rounded whapeztore eliminatingsharp angles. y specific volojectof=.:the invention is t press the vii-near peripheral edges r and lannular aperture mouths of asheet. metal evaporatonunit-ioirounded edges. and, aperture mouths; .formed iaccordingtolthisrinvention and illustrating in dotitedilines -thermanner Linwwhich the unit :is bent ifromiflat sheet form. t

. Figure 2 isa,side;e1evational view. of the evarporater unit-shownin-Eigure 1. r l t l t Figure: 3,-.-is 'an-en1arged fragmentary horizontal cross-sectional view taken along the line III-J-IIIt of Figure g2 and illustrating a uniform .coatingwound 'anaedge ottheiunita 1i-Figll-re 4r-ris aviewrsimilarto-Figurer 3r'but illustratingr the :defic-ient coating-i film F on 'an article .havingasharpedge. l i

t #Figure 51 is: a topl-planview-of:a ldressingtmachine r f or; rounding the-longitudinaledges of-t emloossed weldedstogether' fflat metalsheets forming the bodyiofelthe; evaporator-unit-andillustratring "thepassage of thenmit throughtthermachine.

Figure 6 is an endaelevationai view'ofcthermachine andxembossed welded-together metal sheets passingrthrough the machine l as tshownvin Figure5. l a

1 Figure'lis amenl'arged vertical cross-sectional view taken through on'eform of die for roundin themouths of an aperture in the metal sh-eet shown'in'fiigured l 1 YFigure 8 is a view similar to Figure '7 butiillustrating the die infully closed position and showing the manner inwhich the sheet metal! is pressed tmprbvidea rounded contour-for the aperture.

*' Figure 9 is a view similar to 'Figure' '7 but i'llus trating a modifiedform of dieior rounding the aperturemouths.

Figure lo isa'plan view 'ofan aperturedmetal ysheet illustrating arounded aperturemouth formed in accordance with this-invention.

Figure 11 is a view taken along the line cf. Figure" 10 and illustrating theuniform-protecting film covering the sheet metal.

."Eigure 12 is a view similar toFigure-ll but illustrating the defective protectingdilmfforrned when the aperture-mouthsmresharp. V

' ducts.

As shown on the drawings:

In Figures 1 and 2, the reference numeral I3 designates generally a U-shaped sheet metal evaporator unit defining the side walls and bottom of a sharp freezing chamber I I. The unit is composed of an outer sheet I2 welded, brazed, or otherwise secured to an inner sheet I3.

Prior to securing the sheets I 2 and I3 together, the sheet I2 is embossed to provide flutes I4 defining refrigerant circulating ducts along the side walls and bottom of the unit and semi-cylindrical header depressions I5 and I6 normal to the flutes I4 at the ends of the sheets. a The sheet I2 is also embossed to provide a flut l1 in intersecting'relation with the fiutes I4 to serve as an inlet manifold for supplying refrigerant to the circulating The inner sheet I3 is embossed with semicylindrical depressions I8 and I9 complementary with the depressions I5 and I 6 to cooperate therewith for forming header chambers in the side walls of the unit. The inner sheet is also embossed as at 2f! to provide ducts joining the header chambers. The outer sheet can be further embossed to provide a flute 2| around the side walls and bottom thereof connecting the tops of the top header chambers in the side walls. This flute 2| defines an outlet passageway for spent refrigerant to be removed therethrough from the unit.

As shown in Figure 1, in dotted lines, the unit III is formed by bending, into U-shape, the flat embossed welded-together sheets I2 and I 3 which provide a blank designated generally by the reference numeral 25. formed around a shaping die into the desired evaporator unit shape for providing the-side walls and bottom of a sharp freezing chamber. The upper ends of the side walls of the bent unit age preferably turned in to form hanger flanges 2 As best shown in Figure 5, the fiat blank 25 has apertures 21 at the ends thereof which apertures will be through the flanges 26 when the unit is bent into final form to receive hanging bolts. The blank 25 also has additional apertures therethrough such as 28 to provide for the mounting of a shelf in the unit; 29 to provide for the mounting of a thermostat bulb or other temperature-responsive means on the unit; and

30 to provide for the mounting of a door across the open front face of the unit.

As shown in Figures 5 and 6, the blank 25 has the longitudinal edges 3| thereof acted on by means of a machine 32 composed of a block 33 carrying spaced pairs of grooved rollers 34, 35 and 36 rotatably mounted on vertical axles 31 carried by the block. The rollers each have peripheral rounded grooves 38 therearound. The first pair of rollers 34 is spaced apart for a distance greater than the distance between the second pair of rollers 35 and this second pair of rollers 35 is, in turn, spaced apart for a distance greater than the third pair of rollers 36.

The blank 25 is passed through the machine 32 in the direction indicated by the arrow in Figure 5 so that the first pair of rollers 34 will initially act on the sharp longitudinal edges of the blank and will start to dress the edges. Then, as the blank is pushed through the machine and between the succeeding pairs of rollers the rounded grooves 38 of the rollers will press the edges 3| to conform with the rounded shape of the grooves and thereby eliminate the sharp edges. As shown in Figure 3, the edges of the weldedtogether sheets I2 and I3 will thus have a semicylindrical contour 39. After passage through The blank 25 can be readily the machine 32 the blank 25 is then passed through another machine similar tothe machine 32 but having pairs of rollers spaced to act on the edges 40 of the blank. The resulting blank will therefore have all peripheral edges free from sharp corners and, as shown in Figure 3, a galvanized coating 4| on the finished unit will provide a film which flows evenly all around the.

edges as at 42.

If, on the other hand, as shown in Figure 4 the sheets I2 and I3 had sharp edges 43 at right angles to the faces of the sheet, a galvanizing film 4| 44 and might even break to expose these corners.

From the above descriptions it'will thus be understood that all linear peripheral edges of the blank 25 are dressed to eliminate sharp edges and to provide rounded contours to the edges which will be uniformly covered with a protecting film upon dipping the metal article in the coating material.

It has heretofore been considered necessary-to line all apertures through sheet metal evaporator units with copper ferrules for protectin the sheet metal against corrosion. These ferrules were required even though the units were galvanized inasmuch as the sharpmouths of the apertures would not be uniformly covered with the zinc film. The present invention now eliminate's' the necessity for copper ferrule liners and at the same time insures the formation of.uniformly thick films over the aperture walls.

Thus, as shown in Figures 7 and '8, an aper- 5 ture of the blank 25 such as a hole '21 through the sheets I2 and I3 is dressedin a die for removing the sharp aperture mouths 45. The blank 25 is mounted on a die with the aperture 21 receiving the leading end of the die. This 40 leading end of the die has a quarter-round bevel or groove 41. A top die 48 having a similar leading end with a rounded groove 49 cooperates with the die 46. The dies 43 and 48 are telescoped by sleeves 50 and 50a respectively which have rounded leading ends 5L The leading ends 5| of the sleeves press into the faces of the sheets I2 and I3 to flow a metal into the aperture 21. As the dies close, the grooves 41 and 49 form a semi-cylindrical pocket which receives metal pressed from the faces of the sheet by the sleeves 50 and 50a to form a rounded periphery 52 for the aperture 21.. The metal pressed by'the leading ends 5| of the sleeves, together with the metal pressed from the sharp corners 45 will completely fill the die cavities as shown in Figure 8.

All of the apertures 21 to 30 of the blank 25 may be treated in a similar manner to dress the aperture mouths for eliminating all sharp corners.

Alternatively, as'shown in Figure 9, the sleeves 50 and 50a may be omitted from the dies 46 and 48. The quarter-round grooves 41 and 49 ofthe dies will dress the sharp corners 45 of theaperture 21 sufiiciently to form a rounded contour,

would be quite thin at the sharp corners V as shown in Figure 12 the comers 45 are allowed to remain around the aperture mouths, thefllm 4| willnot uniformly flow through the aperture details of the invention may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claim. v

I claim as my invention: i

In the method of manufacturing an evaporator unit including the steps of embossing apair of fiat, thin metallic plates to provide refrigerant ducts and headers therefor when said plates are united, providing mating apertures in said plates mated relationship, bending said united plates to form an evaporator unit including the side and bottom walls of a quick-freeze chamber and. providing a protective coating over the surface of said unit, the stepof preparing said unitifor the application of said protective coating to insure a uniform coverage thereover and particularly over the edges of the mating apertures and over the mating peripheral edges of said unit, which edges are initially sharp and therefore diflicult to cover completely and uniformly by said protective coating, which step comprises rounding the corners at all peripheral edges and aperture edges whilethe united plates are in a flat state by forcing metal simultaneously from opposite sidesof the evaporator unit at each edge toward the junction between said plates at said each edge so as to round the corners at both go sides of the peripheral edges and aperture edges and thereby minimize the possibility of any sharp corners projecting through said protective coat- BERNARD c. JOHNSON.

for mounting purposes, uniting said plates in i 

